1. Field of the Invention
The present invention concerns a system in which a plurality of electronic equipments are connected by way of a bus and communication is conducted between each of the electronic equipments and, more specifically it relates to a system in which an originally developed application is made usable also by other company under a license contract.
The present invention concerns a system in which a plurality of electronic equipments are connected by way of a bus capable of transmitting information signals and control signals, and communication is conducted between each of the electronic equipments and, more specifically, it relates a technique for carrying command/status for controlling an analog equipment on a control signal of a predetermined format.
2. Description of Related Art
As a system in which a plurality of electronic equipments are connected by ways of a bus and communication is conducted between each of the electronic equipments, a communication system using an IEEE-1394 serial bus is considered. In the communication using the IEEE-1394 serial bus, electronic equipments such as digital video tape recorders, digital video cameras, digital television receivers and personal computers (hereinafter referred to simply as equipments) are connected by way of the IEEE-1394 serial bus and communication is conducted between each of the equipments for information signals such as digital audio/video signals and control signals such as connection control commands.
In the communication system using the IEEE-1394 serial bus, a vendor unique command is provided in order that each of manufacturers attains an application of its own (basic command to provide compatibility between each of companies is defined separately from the vendor unique command). It is specified that a company ID is attached to a packet of a vendor unique command for indicative the manufacturer. Accordingly, the application attained by using the vendor unique command is basically valid only for the manufacturer.
Even an originally developed application is sometimes valid for other companies. When an application has no such general applicability that it is registered as a common command, the originally developed application by a certain manufacturer is sometimes intended to be used also by other manufacturer. When other manufacturer uses a vendor unique command for the application, a company ID of the manufacturer developing the application has to be used.
Then, if the manufacturer developing the application admits other manufacturer to use the company ID under a formal license contract, other company also enables to use vendor unique commands other than the application.
The present invention has been accomplished in view of the foregoing problem and provides an equipment that enables the use of other company on every originally developed application, as well as a controlling method therefor.
As a system in which a plurality of electronic equipments are connected by way of a bus and communication is conducted between each of the electronic equipments, a communication system using an IEEE-1394 serial bus is considered. In the communication system using the IEEE-1394 serial bus, electronic equipments such as digital video cassette records (hereinafter "video cassette recorder" is simply referred to as "VCR"), digital video cameras, digital television receivers and personal computers (hereinafter referred to simply as equipments) are connected by way of the IEEE-1394 serial bus and communication is conducted between each of the equipments for information signals such as digital audio/video signals and control signals such as connection control commands.
In the communication system using the IEEE-1394 serial bus, AV/C-CTS (Audio Video/Control Command Transaction Set) which is a command transaction set for controlling an audio/visual equipment can be used in an equipment control protocol of a digital interface. Then, the operation of a digital VCR or the like can be controlled from other equipment in the communication system by using this. AV/C-CTS is a "mode drive type" command set designating a final status to a digital VCR, for example, such that "go to playback pause (PB PAUSE) status".
On the other hand, as a system for controlling the operation of an analog VCR from the outside, LANC (Local Application Control Bus System: registered trade mark) has been popularized at present. In LANC, if it is intended to put an analog VCR, for example, to PB PAUSE status, a "PAUSE" command is sent after confirming that it is in the playback status. LANC is a so-called "command drive type" command set.
Digital VCR under development at present for commercialization are designed so as to cope with both AV/C-CTS and LANC.
However, even in the control by way of a digital interface, all operation controls can not be covered by the mode drive type command. For example, in a case of channel selection by a tuner, a command indicative of a channel number or a station name is sent in the mode drive type, but broadcastings per se are different and channels preset to equipments are also different depending on areas. Further, an infrared remote commander as a point of contact with user's operation (hereinafter "remote commander" is simply referred to as "remocon") is command driven and requires a command drive type command for instruction of channel up/down such as "Channel +"/"Channel -".
Then, as a command set for the digital interface, it may be considered to dispose a command drive type command set separately from AV/C-CTS but, in this case, since a digital VCR as an equipment to be controlled correspond to three kinds of command sets, load on a microcomputer for processing the commands (hereinafter "microcomputer" is simply referred to as "micon") is increased.
The present invention has been accomplished in view of the foregoing problem and it is an object thereof to introduce a command drive type command set without increasing the burden on a micon for processing the commands.